The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
In an apparatus for compressing video data, intra encoding is performed in a way to effectively compress, through a transform technique, quantization and entropy coding processes, residual signals obtained by effectively removing spatial redundancy out of frames or blocks.
Representative intra coding methods include JPEG (Joint Photographic coding Experts Group) which is a compression method based on block-based discrete cosine transform (DCT) and JPEG2000 with an enhanced encoding effectiveness by a wavelet-based arithmetic coding scheme. Recently, it is known to the inventor(s) that the performance of intra encoding method through direction-based extrapolation prediction of H.264/AVC is most superior.
The intra encoding through the direction-based extrapolation prediction of H.264/AVC performs an extrapolation prediction by using pixels on the left and upper portions (A˜M) in which encoding/decoding is completed based on the 9 directions including DC prediction (Mode 2) as illustrated in FIG. 1. That is, the extrapolation prediction of a pixel value in a block is performed by way of filling the pixel with values of the pixels in the left and upper portions according to the predicted direction. For example, in Mode 0, since the extrapolation prediction is performed in a vertical direction, the 4×4 block in FIG. 1 is filled with the values of A, B, C, D which are pixels in the upper portion in a direction of the arrows.
The inventor(s) has noted that in order to support a super-high resolution, there have been proposals for various block partitioning methods and encoding methods supporting intra prediction modes in various directions. In this case, the inventor(s) has experienced that a higher compression rate can be achieved by performing intra prediction to finer images, but not without incurring additional information for decoding the same, that is, an amount of signals such as a block partitioning method and an intra prediction mode, which makes it difficult to enhance the overall compression rate. The inventor(s) has, therefore, experienced that in order to achieve the higher compression rate, it is possible to reduce the total encoding bit amount by eliminating the repetitive elements of the additional information.